/*
 * ice4j, the OpenSource Java Solution for NAT and Firewall Traversal.
 *
 * Copyright @ 2015 Atlassian Pty Ltd
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.ice4j.attribute;

import org.ice4j.StunException;

/**
 * The requested address family attribute defined in RFC 6156.
 *
 * @author Aakash Garg
 */
public class RequestedAddressFamilyAttribute extends Attribute {
	/**
	 * Attribute Name.
	 */
	public static final String NAME = "REQUESTED-ADDRESS-FAMILY";

	/**
	 * The length of the data contained in this attribute.
	 */
	public static final char DATA_LENGTH = 1;

	/**
	 * The IPv4 family type.
	 */
	public static final char IPv4 = 0x01;

	/**
	 * The IPv6 family type.
	 */
	public static final char IPv6 = 0x02;

	/**
	 * The address family value.
	 */
	char family = IPv4;

	/**
	 * Constructor.
	 */
	protected RequestedAddressFamilyAttribute() {
		super(REQUESTED_ADDRESS_FAMILY);
	}

	/**
	 * Returns the length of this attribute's body.
	 * 
	 * @return the length of this attribute's value (1 byte).
	 */
	@Override
	public char getDataLength() {
		return DATA_LENGTH;
	}

	/**
	 * Returns the human readable name of this attribute. Attribute names do not
	 * really matter from the protocol point of view. They are only used for
	 * debugging and readability.
	 * 
	 * @return this attribute's name.
	 */
	@Override
	public String getName() {
		return NAME;
	}

	/**
	 * Compares two TURN Attributes. Attributes are considered equal when their
	 * type, length, and all data are the same.
	 * 
	 * @param obj
	 *            the object to compare this attribute with.
	 * @return true if the attributes are equal and false otherwise.
	 */
	@Override
	public boolean equals(Object obj) {
		if (!(obj instanceof RequestedAddressFamilyAttribute))
			return false;

		if (obj == this)
			return true;

		RequestedAddressFamilyAttribute att = (RequestedAddressFamilyAttribute) obj;

		if (att.getAttributeType() != getAttributeType() || att.getDataLength() != getDataLength()
		/* compare data */
				|| att.family != family)
			return false;

		return true;
	}

	/**
	 * Returns a binary representation of this attribute.
	 * 
	 * @return a binary representation of this attribute.
	 */
	@Override
	public byte[] encode() {
		byte binValue[] = new byte[HEADER_LENGTH + DATA_LENGTH];

		// Type
		binValue[0] = (byte) (getAttributeType() >> 8);
		binValue[1] = (byte) (getAttributeType() & 0x00FF);
		// Length
		binValue[2] = (byte) (getDataLength() >> 8);
		binValue[3] = (byte) (getDataLength() & 0x00FF);
		// Data
		binValue[4] = (byte) family;

		return binValue;
	}

	/**
	 * Sets this attribute's fields according to attributeValue array.
	 * 
	 * @param attributeValue
	 *            a binary array containing this attribute's field values and
	 *            NOT containing the attribute header.
	 * @param offset
	 *            the position where attribute values begin (most often offset
	 *            is equal to the index of the first byte after length)
	 * @param length
	 *            the length of the binary array.
	 * @throws StunException
	 *             if attrubteValue contains invalid data.
	 */
	@Override
	void decodeAttributeBody(byte[] attributeValue, char offset, char length) throws StunException {
		if (length != DATA_LENGTH) {
			throw new StunException("length invalid: " + length);
		}

		family = (char) (attributeValue[offset] & 0xff);

		if (family != IPv4 && family != IPv6) {
			// instead throw TurnException
			throw new StunException("invalid family value: " + family);
		}
	}

	/**
	 * Gets the address family value
	 * 
	 * @return family the address family value
	 */
	public char getFamily() {
		return family;
	}

	/**
	 * Sets the address family value
	 * 
	 * @param family
	 *            the address family value to set
	 * @return true if argument is IPv4 or IPv6 otherwise false
	 */
	public boolean setFamily(char family) {
		if (family == IPv4 || family == IPv6) {
			this.family = family;
			return true;
		} else {
			return false;
		}
	}

}
